1. Field of Invention
The invention relates to a light-emitting diode (LED) apparatus having a current spreading layer with a micro/nano rugged layer, and a manufacturing method thereof.
2. Related Art
A light-emitting diode (LED) apparatus is a lighting apparatus made of semiconductor materials. The LED apparatus pertains to a cold lighting apparatus, has the advantages of low power consumption, long lifetime, light response speed and small size, and can be manufactured into an extremely small or array-type apparatus. With the continuous progress of the recent technology, the application range thereof covers an indicator of a computer or a house appliance product, a backlight source of a liquid crystal display (LCD) apparatus, a traffic sign or a vehicle indicator.
However, the current LED apparatus still has the problems of the poor light-emitting efficiency and the low luminance. What causes the poor light-emitting efficiency is that the light emitted from the LED is the omni-direction light and is not simply focused on a certain location. In addition, only a portion of the light generated by the LED can be outputted, and the other portion of the light is absorbed due to reflection. Consequently, the luminance of the LED apparatus is decreased, and the heat generated by the LED apparatus is also increased.
In general, the LED apparatus may be a flip-chip type LED apparatus, a vertical type LED apparatus or a front-side type LED apparatus. In order to solve the problem of the low light emitting efficiency caused by the reflection, the following technology has been proposed. As shown in FIG. 1, a LED apparatus 1, a vertical type LED apparatus, has an n-type semiconductor layer 121, an active layer 122 and a p-type semiconductor layer 123 in sequence formed on a surface of a substrate 11. Next, a current spreading layer 13 is formed on the p-type semiconductor doping layer 123, and a first electrode 14 and a second electrode 15 are respectively formed on the current spreading layer 13 and the other surface of the substrate 11.
In the above-mentioned structure, the light outputted from the active layer 122 cannot be emitted out of the LED apparatus 1 until passing through the p-type semiconductor layer 123 and the current spreading layer 13. In addition, the p-type semiconductor layer 123, the current spreading layer 13 and the refractive index of the air are not properly matched, the total reflection may occur when the light is being emitted out, thereby decreasing the light outputting efficiency.
Therefore, there is a need to provide a light-emitting diode (LED) apparatus capable of decreasing total reflection of light so as to increase the light outputting efficiency, and a manufacturing method thereof.